Diarylthiazolo[3,2- a ]pyridin-5-ones: All-Visible-Light-Activated Turn-off Mode Fluorescent Photoswitches with Near-Quantitative Conversion Efficiency

Abstract Two photochromic diarylethenes bearing a thiazolo[3,2-a]pyridin-5-one core were successfully synthesized. These compounds exhibit reversible photochromism in solution and solid-state films, as well as distinct turn-off fluorescence switching behavior under all-visible-light irradiation. Impressively, both derivatives achieve near-quantitative photocyclization efficiency and excellent photofatigue resistance upon alternating light stimulation.